JSFiddle - React, Tailwind, and code Playground

by harsh dand

HTML

<!DOCTYPE html>
<html>
    <head>
        <title>Demo</title>
        <meta charset="utf-8" />
    </head>
    <body>
   
    <textarea id ="text" rows=10 cols="50" onselect="getTextSelection(this);">aaaaaaaaaaaaaaaaaa</textarea>
    </body>
</html>

JavaScript

function getTextSelection(el) {
        var start = 0, end = 0, normalizedValue, range,
            textInputRange, len, endRange;

        if (typeof el.selectionStart == "number" && typeof el.selectionEnd == "number") {
            start = el.selectionStart;
            end = el.selectionEnd;
        } else {
            range = document.selection.createRange();

            if (range && range.parentElement() == el) {
                len = el.value.length;
                normalizedValue = el.value.replace(/\r\n/g, "\n");

                // Create a working TextRange that lives only in the input
                textInputRange = el.createTextRange();
                textInputRange.moveToBookmark(range.getBookmark());

                // Check if the start and end of the selection are at the very end
                // of the input, since moveStart/moveEnd doesn't return what we want
                // in those cases
                endRange = el.createTextRange();
                endRange.collapse(false);

                if (textInputRange.compareEndPoints("StartToEnd", endRange) > -1) {
                    start = end = len;
                } else {
                    start = -textInputRange.moveStart("character", -len);
                    start += normalizedValue.slice(0, start).split("\n").length - 1;

                    if (textInputRange.compareEndPoints("EndToEnd", endRange) > -1) {
                        end = len;
                    } else {
                        end = -textInputRange.moveEnd("character", -len);
                        end += normalizedValue.slice(0, end).split("\n").length - 1;
                    }
                }
            }
        }
        alert("start :" + start + " End :" + end);
    }